I dont think players should have to decide what is "abuse" and what is not. If MMs decide to go bananas and kill everything on sight they should be able to imho. They as any guild should be coded so that there is always a good balance no matter what guild. So if mages go bananas they should have a weakness or counter that make them as killable as those they are murdering.
Giving players "abusable" powers and then expect them to not use them is just silly. I never understood that.
Use powers responsibly? Come on? Its like giving counterstrike players a bazooka but hope they will use it responsible and not kill too many of their opponents. The point of a bazooka is till kill your opponents! Of course they will use it.
No really, players should be able use abilities given to them. If it is called "abuse" it is the fault of the game design, not the players.
Harassment is something else and is clearly defined in the rules. But just using your abilities for whatever you like can never be abuse.
A strange feeling, but I am with Freya on this one.

Sorry Chanele I think you're wrong here. Freya can be "blamed" for many things perhaps but not for using abilities given to her. Anger against vamps or MMs or any other guild should imho be directed at those who coded those guilds, not the players in them.